This disclosure relates generally to the field of microelectronics and more specifically to packaging of stress sensitive circuits such as micro-electro-mechanical systems (MEMS).
Semiconductor dies are microscopic electronic devices that are commonly developed in a semiconductor fabrication process. The semiconductor fabrication process may include multiple steps of depositing material layers, patterning by photolithography techniques, and etching the layers to create the required shapes on wafers. A wafer with a large number of semiconductor dies are generated at the conclusion of the fabrication process. The semiconductor dies within a wafer are packaged in a semiconductor package. In wafer-level packaging, the packaging and interconnections is fabricated on the wafer before dicing may (while the semiconductor dies are still part of the wafer). Alternatively, each individual die on the wafer is separated using operations such as wafer back-grinding and wafer dicing before the semiconductor dies are packaged.
The semiconductor dies are packaged in semiconductor packages that are designed to form electrical connections between the die and an underlying substrate (e.g., a printed circuit board (PCB)). The supporting case also protects the dies from contaminations, moisture, and scratches. However, more sensitive dies may need unique packaging considerations. For example, in case of high performance MEMS devices, at least a portion of the die is covered by low modulus materials (e.g., silicone glob top) to protect or mechanically isolate the die against external stresses, which may affect the semiconductor die performance, while still providing a degree of flexibility for the intended vibration, motion or performance of the device.